US20210100508A1

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Info

Publication number: US20210100508A1
Application number: US17/064,104
Authority: US
Inventors: Eeuwe Jan Vos; Dion Ivo de Roo; Alwin Fransen
Original assignee: Sonion Nederland BV
Current assignee: Sonion Nederland BV
Priority date: 2019-10-07
Filing date: 2020-10-06
Publication date: 2021-04-08
Also published as: US12150783B2; EP3806494C0; EP3806494B1; EP3806494A1; CN112702685A; CN112702685B

Abstract

A hearing device such as a receiver-in-ear assembly. The assembly includes a housing having a cavity extending through the housing; an optical transducer mounted in the cavity within a thickness of the housing, the optical transducer being mounted on a circuit board layer such that a spacing exists between a side of the optical transducer and a sidewall of the cavity. The circuit board layer extends underneath the housing and touching the housing such that the optical transducer is held within the cavity without touching the housing. The assembly further includes a protective substance forming a shield over the optical transducer and the cavity, the protective substance configured to affect a field of view of the optical transducer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of European Patent Application Serial No. 19201800.0, filed Oct. 7, 2019, and European Patent Application Serial No. 20154889.8, filed Jan. 31, 2020, both of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present disclosure relates to a hearing device such as a receiver-in-canal assembly or earbuds for positioning in or at an ear canal of a user. The receiver-in-canal assembly includes a housing with at least one cavity and at least one optical transducer mounted within the at least one cavity, such as within a thickness of the housing. The transducer may also lie just below (or above) the thickness of the housing. All embodiments will also be applicable to this position of the transducer.

BACKGROUND OF THE INVENTION

A receiver-in-canal hearing aid is a type of hearing aid that fits at least partially within an ear canal of a user. It includes a speaker or receiver that generates sounds within the ear canal of hearing impaired users. A receiver-in-canal assembly for positioning in or at an ear canal of a user usually does not include an optical sensor within its housing due to manufacturing challenges to miniaturize these sensors for the harsh environment within the ear. The present disclosure provides solutions for improving efficacy of optical sensors/systems embedded within receiver-in-canal assemblies and other hearing devices.

Receiver-in-ear assemblies usually do not include optical sensors for measuring physiological parameters of a user relating health or other conditions. Furthermore, even if an optical sensor is provided on a receiver-in-ear assembly, its efficacy is reduced because light beams from emitters within the optical sensor cannot be properly channeled or amplified to areas of interest within the ear of the user. This is because incorporating a light emitting diode (LED) or detector with an optical amplifier (e.g., a reflector) on a receiver-in-ear assembly is a challenging problem. Firstly, the LED or detector with an optical amplifier has a larger form factor compared to LEDs without optical amplifiers. Embodiments of the present disclosure provides solutions for at least solving this problem and other problems related to embedding optical sensors in receiver-in-ear assemblies.

SUMMARY OF THE INVENTION

A first aspect of the present disclosure provides a hearing device such as a receiver-in-ear assembly or earbud comprising:

a housing comprising one or more wall portions defining an inner space and including a cavity extending through a wall portion of the housing;

a receiver provided in the inner space,

a circuit board layer,

an optical transducer being mounted in the cavity, the optical transducer being mounted on the circuit board layer such that a spacing exists between a side of the optical transducer and a sidewall of the cavity; the circuit board layer extending underneath the wall portion and touching the wall portion such that the optical transducer is held within the cavity and

a protective substance forming a shield over the optical transducer and the cavity, the protective substance configured to affect a field of view of the optical transducer.

The protective element or substance may be a protective substance configured to hermetically seal the assembly and/or affect a field of view of the emitter.

In another aspect, a hearing device is provided for positioning at or partially or fully in ear canal, the device comprising:

a housing including a cavity extending through the housing;

a transducer such as an optical emitter or detector or a sensor being at least partially mounted within a thickness of the housing at the cavity, the transducer being mounted such that a spacing exists between a side of the emitter and a sidewall of the cavity; and

a protective element forming a shield over the transducer and the cavity.

The protective element or substance may be a protective substance configured to hermetically seal the assembly or cavity and/or affect the performance of the transducer.

In this context, a housing may be formed by one or more wall portions. The wall portions define an inner space which is at least partly delimited by the wall portions. An outer surface of the wall portions may form part of an outer surface of the housing and an inner surface of the wall portions may take part in the definition of the inner space.

A receiver is provided in the inner space. Thus, preferably a sound output is provided in the housing also extending from the inner space toward surroundings of the housing. A receiver is a sound generator, typically with dimensions so small that it may be used in hearing aids and RICs. Often, a receiver has a largest dimension of 8 mm or less. The receiver may comprise electrical conductors or the like for transmitting an electrical signal to the receiver. Such conductors may extend from the inner space and to surroundings of the housing.

The housing can have walls or wall portions of a predetermined thickness. Since the cavity extends through the housing wall portion, such as from the inner space to surroundings of the housing at least prior to providing of the transducer and protective element, incorporating an emitter in thin walled housings of receiver-in-ear assemblies is not an issue, as the emitter may be positioned in the cavity and thus not take up space in the inner space of the housing. If the wall portion is straight, the outer and inner surfaces thereof define parallel planes between which the transducer may be provided. In this context “within a thickness of the housing” means that the receiver is positioned inside the cavity and does not extend out of the cavity to any side thereof to extend outside of a thickness of the housing such as at the edges of the cavity.

The circuit board layer may be a so-called PCB and may be stiff or flexible. Often, the circuit board layer has conductors electrically connected to one or more conductors or connectors of the transducer. The circuit board layer extending underneath the wall portion and touching the wall portion such as being attached to or biased toward the wall portion. Then, the optical transducer is held within the cavity, such as fixed therein by engagement between the optical transducer and the circuit board and engagement between the circuit board and the wall portion. The circuit board may have a surface at which the optical transducer is provided and which engages the wall portion.

The transducer may be an emitter such as an LED for emitting photoplethysmogram (PPG) light of a selected wavelength or of multiple wavelengths. The emitter can be mounted in a manner such that a top of the emitter is in line with an outer surface of the housing. Alternatively, the transducer may be a light receiver. Actually, the transducer may comprise both an emitter and a detector/receiver.

Alternatively, multiple transducers may be provided each in a separate cavity, where one or more of the transducers is an emitter and one or more of the transducers is a receiver.

In an embodiment, the sidewall of the cavity includes one or more step portions, one or more straight portions, one or more slanted portions, or any combination thereof. The sidewall can have a straight portion which is substantially vertical for mounting the emitter in a tight fit fashion (with adjacent LED surfaces) and a slanted portion which is generally inclined to enable a desired angle of light emission of no more than 180 degrees depending on the field of view of the emitter. A cross-sectional profile of the sidewall can be piecewise linear with straight portions, slanted portions, etc.

In an embodiment, the sidewall is curved or parabolic shaped. Piecewise construction of the sidewall can also include not just straight portions as previously described but curved portions as well.

In an embodiment, the sidewall of the cavity includes one or more reflective surfaces. The reflective surfaces can reflect light, such as at least 30%, of the emitter at selected light wavelengths, such as red, green and/or near-infra red light and/or a wavelength of 850 nm.

In an embodiment, the one or more reflective surfaces include a suitable material such as plastic of a reflective color, a plastic with reflective particles, metal, a coated surface, or any combination thereof. Composition and surface structure of the one or more reflective surfaces and/or an angle of the one or more reflective surfaces can make the one or more reflective surfaces reflect light of different wavelengths at different reflective angles and different direct or diffuse beam shapes.

In an embodiment, the one or more reflective surfaces can extend below the housing. In some embodiments, all reflective surfaces are under the housing, allowing (at least) part of the housing to be made from a translucent or transparent material, e.g., a transparent plastic, glass, transparent ceramics, etc. The one or more reflective surfaces then may extend along an inner surface of the wall portion(s). In some embodiments, when using transparent material and reflective surfaces underneath the housing, reflective surfaces on the sidewalls or reflective surfaces on an outer surface of the sidewalls are not included in the receiver-in-ear assembly.

In some embodiments, the one or more reflective surfaces is provided under the emitter. In some embodiments, the one or more reflective surfaces is on an outer surface of the housing such as on an outer surface of one or more wall portions. Reflective surfaces according to embodiments of the disclosure can be made from separate reflective parts. Reflective surfaces according to embodiments of the disclosure can be made from a reflective coating or layer deposited or laminated on a surface of the housing, sidewalls, etc.

In an embodiment, the protective substance includes one or more sealing glues. At least one of the one or more sealing glues can fill the cavity and form the shield as an outwardly curved shield. A curvature of the outwardly curved shield can affect the field of view of the emitter. The one or more sealing glues can have different functions, e.g., sealing an inside of the cavity, protecting electronics and the emitter, providing an optical lens, etc. The one or more sealing glues can include potting material, overmould, epoxy/resin/poly urethane, etc.

Alternatively, or additionally, the protective substance can include a lens. The lens may be a plastic lens or a glass lens. The protective substance includes a Fresnel lens, the Fresnel lens forming the shield as a flat surface.

In an embodiment, the radiating element of the emitter is positioned a distance from the circuit board layer such that increasing the distance increases the field of view of the emitter.

Another aspect of the present disclosure provides a hearing device such as a receiver-in-ear assembly or earbud comprising:

a housing including a cavity extending through the housing;

an emitter or detector being at least partially mounted within a thickness of the housing at the cavity, the emitter being mounted on a circuit board layer such that a spacing exists between a side of the emitter and a sidewall of the cavity;

the circuit board layer extending underneath the housing and touching the housing such that the emitter or detector is held within the cavity without touching the housing; and

a protective element forming a shield over the emitter and the cavity.

Clearly, all above considerations, embodiments and situations are equally relevant in this context.

Another aspect of the present disclosure provides a receiver-in-ear assembly comprising:

a housing including a cavity extending through the housing, the housing being made from a transparent material; the housing may comprise one or more wall portions defining an inner space in which a receiver may be provided;

an emitter being mounted within a thickness of the housing at the cavity or in the cavity, the emitter being mounted on a circuit board layer such that a spacing exists between a side of the emitter and a sidewall of the cavity;

the circuit board layer extending underneath the housing or the housing wall portion at the inner space and including a reflective surface, the reflective surface touching the housing or wall portion such that the emitter is held within the cavity without touching the housing; and

a protective substance forming a shield over the emitter and the cavity.

Again, all above considerations, embodiments and situations are equally relevant in this context.

The protective substance may be configured to affect a field of view of the emitter.

A final aspect of the present disclosure provides an assembly for a device to be worn at or in an ear canal, comprising:

- a housing (904), which may comprise one or more wall portions defining an inner space, including a cavity extending through the housing (904), such as through a wall portion of the housing (904), the housing (904) or the wall portion at least partly being made from a transparent material;
- an optical transducer (901) being mounted in or at the cavity, the optical transducer (901) being mounted on a circuit board layer (908) such that a spacing exists between a side of the optical transducer (901) and a sidewall (916) of the cavity;
- a reflective surface (953) extending underneath the housing (904) or the wall portion, such as at a side at the inner space, the reflective surface (953) touching the housing (904) or wall portion; and
- a protective substance (910) forming a shield over the optical transducer (901) and the cavity, the protective substance (910) may be configured to affect a field of view of the optical transducer (901).

The foregoing and additional aspects and implementations of the present disclosure will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments and/or implementations, which is made with reference to the drawings, a brief description of which is provided next.

The foregoing and other advantages of the present disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, and 1C illustrate a receiver-in-canal assembly from different perspectives according to an embodiment of the present disclosure;

FIGS. 1D, 1E, and IF illustrate the receiver-in-canal assembly ofFIG. 1A with dimensional labels;

FIG. 1G is a table providing example ranges for the dimensional labels ofFIGS. 1D, 1E, and 1F;

FIG. 2A illustrates a perspective view of an emitter positioned within a cavity in a housing of the receiver-in-canal assembly ofFIG. 1A without a protective substance;

FIG. 2B illustrates a top view of the emitter inFIG. 2A;

FIG. 2C illustrates a side cutout view of the emitter inFIG. 2A;

FIG. 2D illustrates a cross-sectional view of the emitter inFIG. 2A;

FIGS. 2E and 2F illustrate views of the emitter inFIG. 2B andFIG. 2D, respectively, with dimensional labels;

FIG. 2G is a table providing example ranges for the dimensional labels ofFIGS. 2E and 2F;

FIG. 3 illustrates an emitter location within a cavity of a housing of a receiver-in-canal assembly according to an embodiment of the present disclosure;

FIG. 4 illustrates an emitter location within a cavity of a housing of a receiver-in-canal assembly according to an embodiment of the present disclosure;

FIG. 5A illustrates an emitter-detector system embedded within a receiver-in-canal assembly and light paths from an emitter unit to detectors units according to an embodiment of the present disclosure;

FIGS. 5B and 5C illustrate concept of narrowing field of view according to an embodiment of the present disclosure;

FIG. 6 illustrates a cavity within a housing of a receiver-in-canal assembly with slanted sidewalls according to an embodiment of the present disclosure;

FIG. 7 illustrates a cavity within a housing of a receiver-in-canal assembly with parabolic sidewalls according to an embodiment of the present disclosure;

FIG. 8 illustrates an example of a Fresnel lens for beam shaping according to an embodiment of the present disclosure;

FIGS. 9A, 9B, and 9C illustrate example areas to have reflective surfaces according to an embodiment of the present disclosure;

FIG. 9D illustrates an example of adding reflective surfaces to improve detector efficiency according to an embodiment of the present disclosure;

FIG. 10A illustrates a reflective surface installation in a housing according to an embodiment of the present disclosure;

FIGS. 11A, 11B, and 11C illustrate examples of using reflectors to reduce separation between emitters and detectors according to some embodiments of the present disclosure;

FIG. 12A illustrates shielding a cavity with a premolded window according to an embodiment of the present disclosure;

FIGS. 12B and 12C illustrate light ray tracings according to some embodiments of the present disclosure;

FIG. 12D compares dimensions of two cavities including two different emitters according to some embodiments of the present disclosure;

FIG. 12E illustrates two types of emitters according to an embodiment of the present disclosure;

FIG. 13A illustrates a concept of a critical angle according to an embodiment of the present disclosure;

FIGS. 13B and 13C illustrate light ray tracings according to some embodiments of the present disclosure;

FIG. 13D illustrates light ray tracings for a housing without a reflective surface according to some embodiments of the present disclosure;

FIG. 13E illustrates light ray tracings for a housing with a reflective surface according to some embodiments of the present disclosure;

FIG. 14A illustrates a perspective view of an earbud with optical sensors according to some embodiments of the present disclosure;

FIG. 14B illustrates a cross-sectional view of the earbud inFIG. 14A;

FIG. 15A illustrates a perspective view of an earbud nozzle with optical sensors according to some embodiments of the present disclosure;

FIG. 15B illustrates a cross-sectional view of the earbud nozzle inFIG. 15A

FIG. 16A illustrates a cross-sectional view of an earbud with optical sensors according to some embodiments of the present disclosure;

FIG. 16B illustrates a cross-sectional view of electronic components of the earbud inFIG. 16A;

FIG. 16C illustrates an embodiment of a separation between an emitter and a window in the earbud ofFIG. 16A;

FIG. 16D illustrates a nozzle and electronic components of the nozzle used in the earbud ofFIG. 16A;

FIG. 17A illustrates a perspective view of an earbud with optical sensors according to some embodiments of the present disclosure;

FIG. 17B illustrates a cross-sectional view of the earbud inFIG. 17A;

FIG. 18A illustrates a perspective view of an earbud with optical sensors according to some embodiments of the present disclosure; and

FIG. 18B illustrates a cross-sectional view of the earbud inFIG. 18A.

DETAILED DESCRIPTION OF THE INVENTION

While the present disclosure is susceptible to various modifications and alternative forms, specific implementations have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the present disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

Hearing aids and similar devices are designed to improve hearing by making sound audible to a person with hearing loss. In some instances, a person with hearing loss continually gets worse over the course of using hearing aid devices and systems if the hearing aid devices and systems are not properly calibrated. As such, there should be methods and systems that can monitor at least a portion of the person's auditory system while using a hearing aid device. Receiver-in-canal hearing aid devices are hearing aid devices designed to place a receiver (speaker) inside the ear canal of a patient. The receiver is configured to produce amplified sounds captured from the environment outside of ear by a microphone or some wireless device.

Introducing electronics into an ear canal of a patient can be challenging to both designers of the electronics and the patient. The patient may be concerned with comfort, efficacy of the electronics, stylishness and aesthetics of the electronics, discreetness of the electronics, intrusion of the electronics into regular routine, etc. The designers may be concerned with energy requirements of the electronics, protecting the electronics from moisture and earwax, overall efficacy of the electronics, etc.

Although there may be other overlaps between concerns of the patient and the designers, efficacy of the hearing aid devices is important to both. Efficacy of hearing aid devices can depend on electronic components being used and the biology of the patient. Electronic components can wear out over time, and a patient can become acclimated to stimuli over time thus requiring higher and higher intensities for similar results. There are other sources of changes to a patient's body. For example, a patient can develop complications due to problems with oxygen getting to the tissue, a patient's body might develop resistance to constantly being stimulated in a same area, and so on. There should be ways of monitoring changes in tissue surrounding the ear canal or monitoring vitals within the ear canal to determine how the patient's body is responding over time to hearing aid stimuli. Embodiments of the present disclosure provide a system and method for using an emitter-detector system integrated with a receiver-in-canal hearing aid assembly to monitor a patient. The emitter-detector system can provide biometric information, e.g., heartrate and blood pressure.

An example emitter-detector system for monitoring tissue includes photoplethysmogram (PPG) sensors. A PPG sensor can be a pulse oximeter which illuminates skin and measures changes in light absorption. For example, a light emitting diode (LED) can be used to illuminate skin and a photodetector or photodiode can be used to measure changes in light absorption after the light from the LED interacts with the skin. PPG sensors have numerous applications. PPG sensors monitor blood volume changes in microvascular bed of tissue. PPG sensors can be used for monitoring blood pressure, monitoring heartrate and cardiac cycle of a patient, monitoring respiration of a patient, etc. Embodiments of the present disclosure provide an emitter-detector system small enough to be incorporated in an in-ear or in-ear-canal worn device, including a receiver-in-canal hearing aid assembly for continuous monitoring of a patient, also may be incorporated in any device, RIC, ITE, ITC, earbud, also without receiver/miniature speaker. Although a receiver-in-canal hearing aid assembly is used as an example in describing embodiments of the present disclosure, some embodiments can be applied to in the canal (ITC) and in the ear (ITE) hearing instruments or in situations where no receiver is present.

more emitter locations

102a,102b,102c, . . . , for placing one or more emitters. The one or

more emitter locations

102a,102b,102c, . . . , are cavities in thehousing104.

FIGS. 1D, 1E, and 1F illustrate the receiver-in-canal assembly ofFIG. 1A with dimensional labels.FIG. 1D illustrates a cross section from a back view of the receiver-in-canal assembly100.FIG. 1D identifies areceiver height103H and areceiver width103W.FIG. 1E illustrates ahousing portion length104L of the receiver-in-canal assembly100.FIG. 1F illustrates ahousing portion width104W, a housing portion height104H1, and a housing portion height with bumps104H2.

FIG. 1G is a table providing example ranges for the dimensional labels ofFIGS. 1D, 1E, and 1F. Thehousing portion length104L can range from 6 to 15 mm. Thehousing portion width104W can range from 2 to 8 mm. The housing portion height104H1 and the housing portion height with bumps104H2 can range from 2 to 8 mm. An example value for thehousing portion length104L by thehousing portion width104W by the housing portion height104H1 is 11.0 mm×3.5 mm×4.6 mm. The housing portion height with bumps104H2 for the previous example can be 5.0 mm.

Thereceiver height103W and thereceiver width103H can range from 2 to 5 mm. In some embodiments, dimensions for thereceiver height103W by thereceiver width103H include 2.7 mm×0.98 mm, 2.7 mm×1.96 mm, 3.1 mm×2.55 mm, 2.8 mm×4.09 mm, etc. Receivers can have a length that ranges from 5 mm to 8 mm.

FIG. 2A illustrates a perspective view of anemitter201 positioned within a cavity in thehousing104 of the receiver-in-canal assembly100. The perspective view does not show a protective covering for the cavity. The cavity can have a steppeddesign202. Referring toFIG. 2B, a top view of theemitter201 is provided. Other than the steppeddesign202, the cavity can include spacing, e.g., aspacing206 and aspacing207, between thehousing104 and theemitter201. Thespacing206 and thespacing207 can be, e.g., 0.15 mm. Thespacing206 and thespacing207 can serve as positioning tolerances for theemitter201. Furthermore, the

spacing

206 and207 can serve as capillary distances/gaps for a protective filling, e.g., glue, that holds theemitter201 in place. The cavity in thehousing104 exposes acircuit board layer208. Thecircuit board layer208 can be a flexible circuit board comprising a flexible polymer.

Referring toFIG. 2C, a side cutout view of theemitter201 inFIG. 2A is provided. Examples of theemitter201 include a transmitter for transmitting electromagnetic waves, an LED, an exit of an optical fiber/lightguide (transmitting light generated at a different location), etc. In an example where theemitter201 is an LED, from the side cutout view ofFIG. 2C, theemitter201 can have within it an active or radiatingelement214 and awire212 for connecting the radiatingelement214 to a power source. Theemitter201 can have aceramic base218 for providing structure to theradiating element214. A height of theceramic base218 can be used to adjust a height of the radiatingelement214 in relation to a height or thickness of thehousing104. Theemitter201 can have aclear LED coating220 to protect theradiating element214 and thewire212 from environmental and physical influences. Theclear LED coating220 can be a clear glue or overmould.

InFIG. 2C, theemitter201 is covered with aprotective substance210. Theprotective substance210 fills in spaces within the cavity in thehousing104. Theprotective substance210 can be a glue that contours to the spaces within the cavity. In some embodiments, theprotective substance210 is a glue that forms a lens that directs beams of light coming from theemitter201. Theprotective substance210 is applied to cover all corners and surfaces of theemitter201.

The cavity inFIG. 2C is shown to have sidewalls216. Thesidewalls216 are slanted. The cavity also includes the steppeddesign202. Although two steps are shown in the steppeddesign202, more than two steps can be provided in the cavity. The steppeddesign202 enables theprotective substance210 to remain within the cavity during manufacturing, fostering theprotective substance210 to form a dome around the cavity.

Referring toFIG. 2D, a cross-sectional view of theemitter201 is provided without the radiatingelement214 and thewire212. As shown inFIG. 2D, the cavity completely penetrates thehousing104 such that within the cavity, theemitter201 rests on thecircuit board layer208 and not on thehousing104. An inner surface of thehousing104 interfaces with thecircuit board layer208. Also shown inFIG. 2D, theceramic base218 of theemitter201 is shown to haveelectrical channels217 that connect to thecircuit board layer208.

FIG. 2E is a reproduction ofFIG. 2B with dimensional labels, andFIG. 2F reproducesFIG. 2D with dimensional labels.FIG. 2G provides example ranges for the dimensional labels ofFIGS. 2E and 2F. Anemitter width201W can range from 0.25 mm to 1 mm. Anemitter length201L and anemitter height201H can range from 0.5 mm to 2 mm. A ceramic base height201SH of an emitter can range from 0.1 mm to 0.3 mm. An active height201AH including a ceramic base and a radiating element can range from 0.2 mm to 0.5 mm. A bump protruding height203H1 of a protective substance can range from 0.05 mm to 0.3 mm, and a protruding substance height203H2 from a top of an emitter can be between 0 mm and 1.8 mm.

FIGS. 2E and 2F show a cavity with sidewalls. A bottom width205W1 and a top width205W2 of the cavity can be above 0.25 mm. A bottom length205L1 of the cavity can range from 0.5 mm to 2 mm, and a top length205L2 of the cavity can range from 1 mm to 4 mm. A flat sidewall height205H1 of a flat portion of the sidewall of the cavity can range from 0.05 mm to 0.1 mm. A slanted sidewall height205H2 of a slanted portion of the sidewall of the cavity which also includes the flat sidewall height205H1 can range from 0.1 mm to 0.5 mm.

For an example device, dimension for theemitter width201W by theemitter length201L by theemitter height201H is 0.5 mm×1 mm×0.45 mm. Also dimensions for the ceramic base height201SH is 0.18 mm and that for the active height201AH is 0.33 mm. The bump protruding height203H1 can be 0.33 mm, and the protruding substance height203H2 can be 0.4 mm. The bottom width205W1 and the top width205W2 of the cavity can be 0.8 mm and 1.7 mm, respectively. The bottom length205L1 and the top length205L2 of the cavity can be 1.3 mm and 2.3 mm, respectively. The flat sidewall height205H1 and the slanted sidewall height205H2 can be 0.1 mm and 0.5 mm, respectively.

FIG. 3 illustrates anemitter location300 within a cavity of ahousing304 of a receiver-in-canal assembly according to an embodiment of the present disclosure. The cavity is shown to havestraight sidewalls316. Within the cavity is an emitter with aradiating element314 on aceramic base318. The radiatingelement314 is connected to acircuit board layer308 via awire312. Aprotective cover310 is provided according to embodiments of the present disclosure. The radiatingelement314 being positioned in the configuration ofFIG. 3 is shown to have a field of view (FoV) governed by the angle α. The angle α can be designed based on the thickness of thehousing304, the position of the radiatingelement314 relative to thehousing304, and the shape formed byprotective element310. The higher the position of the radiatingelement314 relative to thehousing304, the larger the angle α, indicating a larger FoV.

FIG. 4 illustrates anemitter location400 within a cavity of ahousing404 of a receiver-in-canal assembly according to an embodiment of the present disclosure. The cavity is shown to have slantedsidewalls416 with astep402. Although one step is shown inFIG. 4, there can be one or more steps as shown above with respect toFIG. 2A. Within the cavity is an emitter with a radiating element414 on a ceramic base418. The radiating element414 is connected to acircuit board layer408 via a wire412. Aprotective cover410 is provided according to embodiments of the present disclosure. The radiating element414 being positioned in the configuration ofFIG. 4 is shown to have a field of view (FoV) governed by the angle β. The angle β can be designed based on the thickness of thehousing404, the position of the radiating element414 relative to thehousing404, the shape formed byprotective element410, the angle of the slant the slantedsidewalls416, size of thestep402.

ComparingFIG. 4 toFIG. 3, addition of the slantedsidewalls416 and thestep402 indicates that the angle β can be designed to be larger than the angle α. As such, the radiating element414 will have a larger FoV compared to theradiating element314. Furthermore, a larger angle β compared to the angle α ensures that the design inFIG. 4 has a larger radius of protective substance when compared toFIG. 3. The larger radius indicates a lower curvature of the surface of the protective substance. An advantage is that less light from the radiating element414 is reflected at the boundary of theprotective substance410 when compared to light from the radiatingelement314 reflected at the boundary of theprotective substance310.

The angle α and the angle β can further be adjusted based on a relative positioning of the radiatingelements314 and414, respectively, to outer edges of the respective cavities ofFIG. 3 andFIG. 4. For example, inFIG. 3, the radiatingelement314 lies below an outer surface of thehousing304 such that thesidewalls316 restrict the FoV to the angle α. On the other hand, inFIG. 4, the radiating element414 also lying below the surface of thehousing404 has the slantedsidewalls416 and thestep402 such that the angle β is larger than alpha. If the radiatingelements314 and414 were positioned relatively higher in comparison to the

housing

304 and404, respectively, then the angles α and β would increase. The positioning of the radiatingelements314 and414 is limited by a maximum size of their respective receiver-in-canal assemblies. That is, a receiver-in-canal assembly should fit the smallest ear canals, thus there is a maximum width and a maximum height for the receiver-in-canal assembly. In some embodiments, emitters are designed to be sunken into cavities as shown inFIG. 3 andFIG. 4 so that a maximum size of a receiver-in-canal assembly is not violated.

Having a wide FoV can introduce some disadvantages. For example,FIG. 5A illustrates a cross-sectional view of a receiver-in-canal assembly with anemitter unit530aand

detector units

530band530cembedded within ahousing504 of the receiver-in-canal assembly.FIG. 5A also illustrates light paths from theemitter unit530ato the

detector units

530band530c. Examples of theemitter unit530ainclude those already described with respect to any ofFIGS. 2A-2D, 3 and 4. The

detector units

530band530ccan take similar form and shape to theemitter unit530a, except that instead of a radiating element (EMT) being the active element, an absorbing element (DET) is the active element. An absorbing element can be a photodetector, an electromagnetic receiver, etc. The

detector units

530band530ccan also look different from theemitter unit530a. For example, the

detector units

530band530ccan have a flat window, can include glue or not include glue, can include reflectors or not include reflectors, etc.

Desired operation of emitter-detector systems involves having an emitter emit signals that interact with a test object then having the detector detect the signals after the interaction with the test object. Signals that do not interact with the test object distort accuracy and introduce errors to the results obtained from emitter-detector systems. InFIG. 5A, theemitter unit530aradiates signals according to a FoV. The desired signals that should reach the

detector units

530band530cshould interact with tissue within the ear, for example, anear canal wall532. That is, alight signal544 from theemitter unit530athat reaches theear canal wall532 and then interacts with theear canal wall532 before reaching thedetector530cis a desired signal. There are multiple ways that signals generated by theemitter unit530acan distort measurement results. For example, alight signal540 can pass through thehousing504 to reach thedetector unit530b. Similarly, alight signal546 can be guided through thehousing504 to reach thedetector unit530c. In another example, alight signal542 can travel directly from theemitter unit530ato thedetector unit530b.

There are multiple ways to alleviate the problems discussed with respect toFIG. 5A. Reflective layer may be built into a flexible PCB. In another example, thehousing504 can be made from opaque material to prevent the light signals540 and546 from reaching the

detector units

530band530c, respectively. FoV of theemitter unit530aand/or the

detector units

530band530ccan be redesigned.FIGS. 5B and 5C illustrate concept of narrowing FoV according to an embodiment of the present disclosure. Overlapping FoV between emitter units and detector units can introduce errors in measurement. InFIG. 5B, a receiver-in-canal block diagram564 contains anemitter unit562 that produces awide beam560a. Theemitter unit562 can be designed to narrow thewide beam560ato anarrow beam560bwhich does not overlap with a FoV of another emitter unit or detector unit. InFIG. 5C, a receiver-in-canal block diagram566 includes an emitter unit and a detector unit on a same side. The emitter unit and the detector unit have wide FoV indicated by the

wide beams

568aand570a. The emitter unit and the detector unit FoV can be adjusted to568band570b, respectively, using some embodiments of the present disclosure.

FIGS. 6 and 7 illustrate designs of cavities for reducing FoV according to some embodiments of the disclosure. InFIG. 6, the cavity in ahousing604 includes slantedsidewalls616. The sidewalls can be slanted at anangle630 with respect to acircuit board layer608. Theangle630 can be at least 90 degrees such that signals reflecting from the slantedsidewalls616 are directed toward a center axis of the cavity. In embodiments where the radiatingelement614 is an active region of an LED, having slantedsidewalls616 increase luminosity around the center axis of the cavity. The slanted sidewalls616 can include deposits of reflecting material to increase amount of light reflected.

FIG. 6 also incorporates a new design for the emitter when compared toFIG. 2C. Theemitter201 inFIG. 2 includes theceramic base218 and theclear LED coating202. InFIG. 6, the emitter can be made smaller by not including a ceramic base, and the active substance (the radiating element614) can be bonded directly to thecircuit board layer608. An example dimensions for theradiating element614 is 0.22 mm length by 0.22 mm width by 0.15 mm height. Manufacturing can be simplified by using one protective substance to fill the cavity rather than having a clear LED coating underneath the protective substance. An advantage of removing the ceramic base from the emitter is that thehousing604 can be made thinner since a height of theradiative element614 is lower than a combined height of a radiative element and a ceramic base.

Referring toFIG. 7, a cavity withparabolic walls716 in ahousing704 is provided.FIG. 7 includes anemitter701 for emitting signals that travel in a FoV indicated by item730. Similar toFIG. 2C, theemitter701 can sit on acircuit board layer708. Signal beams from theemitter701 are narrower due to theparabolic walls716.

Narrower beams can also be obtained via the shaping of a top boundary of a protective substance, e.g., theprotective substance210. Shaping of the top boundary can be achieved, for example, by adding a lens on top (or inside) a glue of the protective substance, or by pressing a shape of a lens into the glue while the glue is solidifying. Theprotective substance210 is dome-shaped. For example, glue can be deposited as theprotective substance210, and once the glue solidifies, it retains the dome shape. In some embodiments, a Fresnel lens according toFIG. 8 can be used to obtain a flat surface instead of a dome-shaped top boundary.FIG. 8 illustrates a dome-shapedlens802 according to embodiments of the present disclosure with atop surface806. A dome-shapedlens802 can be used in instead-of or in-addition to theprotective substance210. Alternatively, a transparent window (e.g., in the form of flat lens or a Fresnel lens804) can be used to cap a cavity in a housing of a receiver-in-canal assembly containing an emitter or a detector. Anouter surface808 of the Fresnel lens can take on a flat shape, parallel to that of the emitter, e.g., theemitter201. Aninner surface810 interfacing with the protective substance can be patterned to encourage narrower signal beams.

In some embodiments, a lens is used to cover or cap a cavity in a housing of a receiver-in-canal assembly containing an optical transducer. The capped cavity can be filled with a sealing glue to environmentally protect the inside of the cavity. Preferably, the capped cavity is filled with clear or transparent glue, epoxy, or adhesive for optimal optical coupling of the lens to the optical transducer. Also preferably, a volume between sides of the optical transducer (e.g., the clear LED coating220) and the housing are filled with clear or transparent glue, epoxy, or adhesive, touching sides of the optical transducer without air bubbles, for optimal optical coupling of the lens to the sides of the optical transducer. The filling up of the volume at the sides of the transducer may be the preferred design not only when there is a lens on top, but also to optimize the coupling of the transducer to the outside of the device.

To further prevent emitted signals from penetrating the housing, one or more reflective surfaces or reflectors can be provided as depicted inFIGS. 9A and 9B. A reflective surface is a surface that reflects incident light that reaches the surface. For example, a surface can be classified as a reflective surface if more than 50% of incident light is reflected, if more than 75% of incident light is reflected, if more than 90% of incident light is reflected, or if more than 99% of incident light is reflected.FIG. 9A illustrates an emitter location within a cavity of ahousing904 of a receiver-in-canal assembly according to an embodiment of the present disclosure. The cavity is shown to have slantedsidewalls916. Within the cavity is anemitter901 with aradiating element914 on aceramic base918. The radiatingelement914 is connected to acircuit board layer908 via awire912. Aprotective cover910 is provided according to embodiments of the present disclosure.

Areflective surface952 can be provided in the cavity. Thereflective surface952 may not extend under thehousing904. In some embodiments, a reflective surface953 (as shown inFIG. 9B) can be provided that extend under thehousing904. The slanted sidewalls916 can havereflective surface950. An area of thehousing904 covered by theprotective substance910 can have areflective substance954 between thehousing904 and theprotective substance910. An area of the housing not covered by theprotective substance910 can have areflective substance956 covering thehousing904.

In some embodiments, thereflective substance956 is used sparingly whereby thereflective substance956 is positioned at areas of the housing near theemitter901 and/or areas of the housing near a detector. In some embodiments, thereflective substance956 can be used anywhere on the housing and not limited to areas proximate to an emitter or a detector.

Using reflective substances according to embodiments of the disclosure allow thehousing904 inFIGS. 9A and 9B to be, at least partly, made from clear material. The remainder of thehousing904 not made from clear material can be made from opaque material to obtain relatively higher bifurcation between an emitter and a detector, minimizing light from the emitter reaching the detector through the housing without interfering with the ear canal tissue of the user (see e.g., the light signals540 and546 ofFIG. 5A) and/or to obtain shielding of the detector from ambient light or other disturbing light sources. In some embodiments, the reflective substance is a metal deposit, e.g., a copper deposit. By having a conductive material as a reflective surface and having the conductive material connected to an electrical circuit or an electrical ground, the conductive material can function as an electromagnetic interference (EMI) shield or a capacitive sensing element. In some implementations, metallic layers of thecircuit board layer908 are used as both a reflective surface and an EMI shield.

Reflective surfaces according to some embodiments can be formed by coating a surface with a reflective coating. Reflective surfaces can be plastic of reflective color for a respective light wavelength, plastic with reflective particles, metal, etc. Using reflective surfaces and substances according to embodiments of the present disclosure provides several advantages. Reflective surfaces prevent light from entering the housing of the receiver-in-canal hearing aid device. Thus, there is no loss associated with absorbing light within the housing or contributing to measurement errors as described with respect to thelight signal546 inFIG. 5A. Reflective surfaces, when added to sidewalls, can increase light intensity by 10 to 20 percent. Reflective surfaces can thus be used to promote focused beams and/or concentrated light. Concentrated light can be beneficial in obtaining biometric data from specific locations in the ear of a patient. Concentrated light improves bifurcation by ensuring that light is not traveling from emitter directly to detector without interacting with tissue in the ear.

In emitters that support multiple wavelengths, reflective surfaces can be used to direct light of different wavelengths in different directions. This can be beneficial because different wavelengths can be targeted to different areas within the ear canal to measure signals at specific locations simultaneously. In some embodiments, reflective surfaces being used within the housing of the receiver-in-canal assembly enables higher measurement efficiency compared to those without reflective surfaces. LEDs with reflectors are too large to fit on small receiver-in-canal assemblies. As such, embodiments of the disclosure provide a design that can be adapted to placement on small receiver-in-canal assemblies. Transparent and/or translucent materials embedded in or for use in, e.g., a transparent housing, glue, sealants, lenses, windows, etc., can have additional optical properties. For example, these materials can form an optical filter to filter out certain wavelengths. In an example, transparent and/or translucent material can filter out ambient light such that the ambient light does not reach a detector.

Since detectors cannot be provided on every square millimetre of a receiver-in-canal assembly, reflective surfaces covering a housing of the receiver-in-canal assembly can guide light signals coming from the ear canal to a detector provided on the housing of the receiver-in-canal assembly. The light signals can bounce back and forth between the reflective surface and the ear canal until they reach a detector.

FIG. 9C illustrates an example of addingreflective surfaces951 on steppedsidewalls915. The stepped sidewalls915 are shown to only include one step, but in other embodiments, the sidewalls can include more than one step and the present disclosure is not limiting a number of steps of the sidewalls. Although thereflective surfaces951 are added to the stepped sidewalls915, other embodiments can be shown where thereflective surfaces951 are not included.

FIG. 9D illustrates an example of addingreflective surfaces972 to acavity970 including adetector971, according to an embodiment of the present disclosure. Thecavity970 is formed in ahousing974 of a receiver-in-canal assembly. Thedetector971 can be covered by awindow980 and can be coupled to acircuit board layer978. The detector can include anactive sensing element984. Thewindow980 can be a sunlight filtering window that filters out ambient light. Thewindow980 can have a roundedcorner976 for improving FoV of thedetector971. Empty space in thecavity970 can be filled withglue982 to hold thewindow980 and thedetector971 in place. In some embodiments,reflective surfaces972 can be added to improve efficiency of light sensed by thedetector971.

FIG. 10A illustrates areflective surface1053 installed in atransparent housing1004 of a receiver-in-canal assembly according to an embodiment of the present disclosure. Thereflective surface1053 can be achieved by folding or wrapping a reflective foil or layer on an inside of thetransparent housing1004. The reflective layer could be omitted in spots where there are other reflective components present, like e.g. the receiver housing.

FIGS. 11A, 11B, and 11C illustrate examples of using reflectors to reduce separation between emitters and detectors according to some embodiments of the present disclosure. Referring toFIG. 11A, anemitter unit1130ais separated from adetector unit1130bby athin wall1104 with

reflectors

1134aand1134bon each side of thethin wall1104.

Referring toFIG. 11B, anemitter unit1130cis separated from adetector unit1130dby areflector1136. Since thereflector1136 is only one reflector, theemitter unit1130ccan be placed closer to thedetector unit1130dwhen compared to the emitter and detector units ofFIG. 11A. Empty spaces in theemitter unit1130cand thedetector unit1130dcan be filled withtransparent glue1137. Referring toFIG. 11C, anemitter unit1130fand adetector unit1130ecan be placed very close to each other and only separated by areflector1138. The emitter units and detector units ofFIGS. 11A-11C can be built on edges of receiver-in-canal assemblies. In comparison toFIG. 5A, use of reflectors inFIGS. 11A and 11B eliminate noise effects of thelight signal546 thus allowing more compact placement of emitter and detector units. In comparison toFIG. 5A, thereflector1138 eliminates noise effects of thelight signal540 thus allowing more compact placement of emitter and detector units.

It should be noted that the transducers inFIG. 11A may be covered by transparent glue only, as protective layer, and that the transducers inFIG. 11B may be covered by, at least, moulded windows and, preferably, glue between the windows and the emitter.

FIG. 12A illustrates shielding acavity1200 including an emitter with apremolded window1210 according to an embodiment of the present disclosure. Thepremolded window1210 can be a lens as previously described. The emitter is mounted on acircuit board layer1208 in thecavity1200 created within thehousing1204 of a receiver-in-canal assembly. Thepremolded window1210 can include one or

more glues

1203a,1203b, . . . . Theglues1203bcan be environmental sealing glue, and theglue1203acan provide optical properties for guiding light from the emitter through thepremolded window1210. Empty spaces within the cavity can be filled withtransparent glue1207 such that there is no air flowing from within the cavity to the environment outside the cavity and/or such that there is an optimal optical coupling between transducer and the outside world.

FIGS. 12B and 12C illustrate light ray tracings of different emitter units according to some embodiments of the present disclosure. Referring toFIG. 12B, an emitter emits light that travels in directions indicated by

rays

1217 and1211. Light can reflect when hitting a boundary or when flowing from one medium to another. As such, some light from theray1211 can be reflected as1213 and some can be passed as1215. Light intensity lost due to the reflection can be about two to six percent. In comparison,FIG. 12C shows no reflections as

rays

1219 and1221 follow a same trajectory as emitted from the emitter. Placingglue1207 as inFIG. 12A will minimizereflections1213.

FIG. 12D compares dimensions of two cavities including two different emitters according to some embodiments of the present disclosure. A first emitter has aceramic base1218 and aclear LED coating1220 and is situated betweenhousing1204a. Aprotective substance1210 covers the first emitter. A second emitter does not have a ceramic base or a clear LED coating (similar to the emitter inFIG. 6) and is situated betweenhousing1204b. As a result, thehousing1204bcan be made thinner than thehousing1204a, and less material can be used as a protective substance for the second emitter compared to theprotective substance1210. InFIG. 12D, length1205L2ais larger than length1205L2b, and height1205H2ais larger than height1205H2b.

FIG. 12E illustrates two types of emitters according to an embodiment of the present disclosure. The first type of emitter can have only anactive element1214 and awire1212. The second type of emitter can have in addition to theactive element1214 and thewire1212, aclear coating1209. The second type of emitter being pre-covered with theclear coating1209 is more resilient to damage of thewire1212 when mounting the second type of emitter in a housing of a receiver-in-canal assembly.

FIG. 13A illustrates a concept of a critical angle according to an embodiment of the present disclosure. When light is traveling from a first medium to a second medium and its angle of incidence at a boundary between the two media is greater than a critical angle θ, then a refracted ray will not emerge in the second medium. For example,light ray1350 has an angle of incidence less than the critical angle θ, so refractedray1352 emerges.Light ray1351 has an angle of incidence greater than the critical angle θ, so it reflects at the boundary as reflectedray1353.

FIGS. 13B and 13C illustrate light ray tracings according to some embodiments of the present disclosure. Referring toFIG. 13B, curvature of a protective layer can influence light escaping from an emitter. InFIG. 13B, the emitter on the left is under a protective layer that has a larger curvature compared to the protective layer covering the emitter on the right. As such, morelight rays1315 escape the protective layer for the emitter on the right compared to the emitter on the left. Thus, morelight rays1313 are reflected at the protective layer for the emitter on the left compared to the emitter on the right.

Referring toFIG. 13B, one of the ways to change the curvature radius may be to select a corresponding material.

Referring toFIG. 13C, light efficiency for light escaping the emitter can be increased by using reflectors. Three designs, a first design without a protective layer, a second design with aprotective layer1310, and a third design with aprotective layer1310 andreflectors1340 are provided. In the first design,light rays1313aare reflected and will eventually be absorbed by a housing whilelight rays1315aescape. In the seconddesign light rays1313bare reflected and will eventually be absorbed by the housing whilelight rays1315bescape. In the thirddesign light rays1317care reflected by the protective layer but then captured and reflected by thereflectors1340 aslight rays1319c. As such,

light rays

1315cand1319cescape whilelight rays1313care captured. When comparing brightness of the three designs, the second design can be five percent brighter than the first design, and the third design can be twenty-three percent brighter than the first design.

FIG. 13D illustrates light ray tracings for ahousing1304 according to some embodiments of the present disclosure. Light from an emitter in a cavity of thehousing1304 hits anear canal wall1370 and can bounce around in theear canal wall1370, picking up biometric signals. The light can then exit theear canal wall1370 as

light rays

1375 and1377. Thelight ray1375 misses the detector and is absorbed by thehousing1304 while thelight ray1377 is sensed by the detector.

FIG. 13E illustrates light ray tracings for ahousing1304 with areflective surface1342 according to some embodiments of the present disclosure. Similar situation asFIG. 13D above except thereflective surface1342 prevents light ray1373 from being absorbed by thehousing1304. Instead the light ray1373 is reflected aslight ray1371, further picking up biometric signals in theear canal wall1370 before returning to the detector as part of thelight ray1377.

In some embodiments, a goal is to reflect light of wavelengths used by a PPG sensor (e.g., wavelengths at near infrared 850 nm, green or red). Minimum reflectance can be about 30 to 40 percent, acceptable reflectance can be 75 percent, good reflectance can be about 90 percent, and excellent reflectance can be above 97 percent. Thickness of any layer or housing material can be determined by an amount of light reflected from the layer, therefore, a minimum thickness of any layer can be set based on light reflected from the material. For example, 50 percent reflectivity can be set as a minimum with 90 percent set as ideal. Material thickness for the housing can then be designed to achieve desired reflectivity. Maximum thickness of material can be determined based on design, production limitations, and cost limitations. Examples of these limitations may include fitting rate of a hearing aid device in the ear canal, being able to bend a metallic part, cost of evaporating gold, etc.

For example, the layer thickness may be:

metal (e.g. gold): ˜50 nm;

paint/ink: ˜10-50 μm;

for plastics, the thickness may be dependent on material and filler. Often, the plastic thickness is determined by maximum build size, and plastic is usually partly transparent for our common wall thicknesses of 0.2 mm or 0.35 mm (for small and large features respectively).

Embodiments of the disclosure can not only be used in hearing aid devices but can be incorporated in earbuds.FIG. 14A illustrates a perspective view of an earbud1400 with optical sensors according to some embodiments of the present disclosure. The earbud1400 can include atransparent dome1408, ahousing1406, and one or more emitters positioned along a nozzle of the earbud1400.

Items

1402a,1402b,1402crepresent transparent windows where emitters emit light, anditem1404 represents a transparent window for a detector to collect light.FIG. 14B illustrates a cross-sectional view of the earbud1400 inFIG. 14A. The earbud1400 can include aflexible circuit board1410 connected to emitters and adetector1412.

FIG. 15A illustrates a perspective view of an earbud nozzle with optical sensors according to some embodiments of the present disclosure. The earbud nozzle can replace the earbud nozzle ofFIG. 14A.FIG. 15B illustrates a cross-sectional view of the earbud nozzle inFIG. 15A. The earbud nozzle inFIG. 15A has a thick housing with atransparent window1502, anemitter1504, adetector1508, and awindow1510 for thedetector1508. Aspeaker1506 can be provided in the earbud nozzle for providing sound that travels through asound channel1512.

FIG. 16A illustrates a cross-sectional view of anearbud1600 with optical sensors according to some embodiments of the present disclosure. Theearbud1600 includes anozzle1614 holding aflexible circuit board1620 and a speaker/receiver1606.FIG. 16B illustrates a cross-sectional view of electronic components of theearbud1600 ofFIG. 16A. Anemitter1604 is provided on theflexible circuit board1620. Adetector1608 is provided on theflexible circuit board1620. A spacing can exist between theemitter1604 and the housing of thenozzle1614.FIG. 16C illustrates an embodiment of the spacing between theemitter1604 and awindow1602 ofFIG. 16B. The spacing can be filled with alight guide1605. Thelight guide1605 can be, for example, glue, plastic, air, etc.FIG. 16D illustrates thenozzle1614 and electronic components of thenozzle1614 ofFIG. 16A-16B. Thenozzle1614 can have guides that allow theflexible circuit board1620 to slide into thenozzle1614.

FIG. 17A illustrates a perspective view of anearbud1700 with optical sensors according to some embodiments of the present disclosure.FIG. 17B illustrates a cross-sectional view of theearbud1700 inFIG. 17A. Theearbud1700 includes a single dome, and an emitter can be placed atlocation1701.

FIG. 18A illustrates a perspective view of anearbud1800 with optical sensors according to some embodiments of the present disclosure.FIG. 18B illustrates a cross-sectional view of theearbud1800 inFIG. 18A. Theearbud1800 includes two domes withdome flanges1816. The emitter can be placed atlocation1801 underneath adome flange1816. One or both of thedome flanges1816 can be transparent for the wavelength used by the sensor.

Embodiments of the present disclosure are described with respect to positioning an emitter within a receiver-in-ear assembly. Similar concerns with positioning the emitter within the receiver-in-ear assembly exist for positioning a detector within the receiver-in-ear assembly. As such, various techniques and embodiments described can be combined for designing or achieving desired field of views for emitters and/or detectors.

All embodiments described in this patent applications are also working where there is direct (physical) contact between an optical transducer and human tissue.